Definition

A cataract is a clouding of the eye's lens. It leads to decreased vision. The lens of the eye focuses an image onto the retina at the back of the eye. This is where an image is processed, and then sent to the brain.

As the cataract matures, it often causes glare, and decreased vision, contrast, and color sensitivity.

Causes

The lens of the eye is made of mostly water and protein. The protein is arranged in a way that keeps the lens clear so light can pass through it. A cataract forms when some of the protein clumps together and starts to cloud an area of the lens. A cataract won't spread from one eye to the other, although most people develop cataracts in both eyes at similar times.

Symptoms

When a cataract is in the early stages, you may not notice any changes in your vision. Cataracts tend to mature slowly. Vision gets worse gradually. Some people with a cataract find that their close-up vision suddenly improves. This is only temporary. Vision is likely to get worse as the cataract becomes cloudier. Because the decrease in vision is gradual, many people do not realize that they have a cataract until it is discovered during a routine eye examination.

A cataract may cause:

Cloudy or blurry vision

Colors seem faded or images appear with a yellow tint

Poor contrast

Poor night vision

Difficulty reading

Double or multiple vision—this symptom often goes away as the cataract matures

These symptoms can also be signs of other eye problems. If you have any of these symptoms, check with your eye care professional immediately.

Diagnosis

The only way to diagnose a cataract is to have an eye examination. Your eye doctor will examine the lens or do some tests to learn more about the structure and health of your eye.

A comprehensive eye examination for cataracts usually includes:

Visual acuity assessment test (VAT)—To assess distant vision.

Slit lamp exam—To magnify the eye.

Tonometry—To assess fluid pressure inside the eye. Increased pressure may be a sign of
glaucoma
.

Dilated eye exam—To evaluate the lens and the structures of the back of the eye.

Treatment

For an early cataract, vision may be improved by using different eyeglasses, magnifying lenses, or stronger lighting. If these measures don't help, or if vision loss interferes with daily activities such as driving, reading, or watching TV, surgery is the only effective treatment.

Cataract surgery
involves waiting until you are ready to have to have it so that it doesn't harm your eye. While you wait, your cataract will get cloudier with time.

Cataract surgery is almost always performed in one eye at a time. After the cloudy lens is removed, the eye surgeon places an intraocular lens (IOL) in its place. An IOL is a clear lens that requires no care and becomes a permanent part of your eye.

After cataract surgery, most people need reading glasses or for distance vision. There is a relatively new option, multifocal intraocular lenses, which focus for both near and far distances in the same lens. Many who receive multifocal intraocular lenses may not need to wear glasses.

Prevention

To help reduce your chance of a cataract:

If you smoke, talk to your doctor about how to successfully quit.

Keep chronic conditions under control by following your treatment plan.

Wear a hat and UV-protected sunglasses when outdoors.

Talk to your doctor about vitamins or supplements with antioxidants.

Get regular eye exams.

Revision Information

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.